"If a cannabis plant is affected by a calcium deficiency for too long, it may begin to show the following symptoms due to the lack of calcium.
Stems become weak or flimsy and may crack easily
Stems become hollow or show inner signs of decay
Plant does not stand up well to heat
Flowers/buds do not develop fully, or development is slow
Roots appear weak or under-developed
In severe calcium deficiencies, parts of roots may even die off or turn brown
Roots are more susceptible to root problems like slimy root rot
Cannabis tends to like high levels of calcium, so it is unusual to feed too much calcium when using normal amounts of nutrients and/or regular soil. There are not many known cases of cannabis calcium toxicity (too much calcium), however too much calcium can cause the plant to lock out other nutrients, so it's important not to go overboard.."
This is usually paired with a magnesium deficiency, Which it looks you have that as well.
Best bet is to just add your nutes to your water like how you would normally ( include your weekly nutes) and let the PH stay where it is. Its bad to try and change the PH with PH down or up because everything you add to your water changes the PH and the can change how much of the PH down or up you need to add, so I've even seen in my 1 gal jug after adding nutes I added a drop of PH down and I mean a drop only and my PH was down at 4.3 lol
So to the people who are not sure what the PH is I wouldn't try and frig with it